The Characteristics of Gas-Water Two-Phase Radial Flow in Clay-Silt Sediment and Effects on Hydrate Production

Many hydrate-bearing sediments in the Shenhu area of the South China Sea are featured with unconsolidated clayed silt, small particle size, and high content of clay, which can pose a great challenge for gas production. In order to investigate the gas-water relative permeability in clay-silt sediments, through a radial flow experiment, samples from the target sediment in the Shenhu area were selected and studied. The results show that the irreducible water saturation is high and the influence of the gas-water interaction is obvious. The relative permeability analysis shows that the two-phase flow zone is narrow and maximum gas relative permeability is below 0.1. The flow pattern in clay-silt sediment is more complicated, and the existing empirical models are inadequate for flow characterization. The depressurization method to extract a hydrate reservoir with clay-silt sediments faces the problem of insufficient production capacity. Compared with the ordinary hydrate reservoir with sandstone sediment, the hydrate reservoir with clay-silt sediment has a low permeability and poor gas flow capacity. The gas-water ratio abnormally decreases during the production. It is urgent to enhance production with cost-effective measures.

[1]  R. Al-Raoush,et al.  3D synchrotron computed tomography study on the influence of fines on gas driven fractures in Sandy Sediments , 2020 .

[2]  H. Bian,et al.  Permeability Evolution at Various Pressure Gradients in Natural Gas Hydrate Reservoir at the Shenhu Area in the South China Sea , 2019, Energies.

[3]  H. Ramézani,et al.  Influence of the Clay Content and Type of Algerian Sandstone Rock Samples on Water–Oil Relative Permeabilities , 2019, Energy & Fuels.

[4]  Jianchao Cai,et al.  Fractal characteristics of unsaturated sands − implications to relative permeability in hydrate-bearing sediments , 2019, Journal of Natural Gas Science and Engineering.

[5]  H. Singh,et al.  A Nonempirical Relative Permeability Model for Hydrate-Bearing Sediments , 2018, SPE Journal.

[6]  Hailong Lu,et al.  The first offshore natural gas hydrate production test in South China Sea , 2018 .

[7]  J. Okajima,et al.  Construction and simulation of reservoir scale layered model for production and utilization of methane hydrate: The case of Nankai Trough Japan , 2018 .

[8]  Z. Hui,et al.  The methane hydrate accumulation controlledcompellingly by sediment grain at Shenhu, northern South China Sea , 2016 .

[9]  Tetsuya Fujii,et al.  Permeability of sediment cores from methane hydrate deposit in the Eastern Nankai Trough , 2015 .

[10]  Jiafei Zhao,et al.  Analysis of the influence of wettability on permeability in hydrate-bearing porous media using pore network models combined with computed tomography , 2015 .

[11]  Yoshihiro Konno,et al.  Experimental evaluation of the gas recovery factor of methane hydrate in sandy sediment , 2014 .

[12]  Chuanhui Li,et al.  Relation between relative permeability and hydrate saturation in Shenhu area, South China Sea , 2014, Applied Geophysics.

[13]  Timothy J. Kneafsey,et al.  Permeability of Laboratory-Formed Methane-Hydrate-Bearing Sand: Measurements and Observations Using X-Ray Computed Tomography , 2011 .

[14]  S. Patil,et al.  Experimental investigation of gas-water relative permeability for gas-hydrate-bearing sediments from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope , 2011 .

[15]  Yiping Song,et al.  The Measurement of Permeability of Porous Media with Methane Hydrate , 2011 .

[16]  Wang Jinlian.  GAS HYDRATE SATURATION AND ITS RELATION WITH GRAIN SIZE OF THE HYDRATE-BEARING SEDIMENTS IN THE SHENHU AREA OF NORTHERN SOUTH CHINA SEA , 2011 .

[17]  Sun Liang-tian.  AN EXPERIMENTAL STUDY ON RELATIVE PERMEABILITY CURVE FOR UNSTEADY-STATE GAS DISPLACEMENT BY WATER , 2007 .

[18]  Hitoshi Tomaru,et al.  Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: Constraints from ODP Leg 204 , 2004 .

[19]  E. D. Sloan,et al.  Fundamental principles and applications of natural gas hydrates , 2003, Nature.

[20]  Timothy S. Collett,et al.  Intrapermafrost gas hydrates from a deep core hole in the Mackenzie Delta, Northwest Territories, Canada , 1995 .